Question about sand & polish ABS Plastic

[bmklawt]

I have decided to sand and polish the ABS plastic in the bathroom.
I have started wet sanding with 320 grit paper which has gotten rid of the yellow, the parts are now white, I am planning on finishing with 800 then 1200 grit paper and polish.

I was wondering what are the con's of not polishing or stopping after the 320, 800 or 1200 grit sanding, will it hold dirt more easily or be harder to clean?

Before and after picture:

[Furzwo]

My husband (plasticman), he works with abs and other plastics at our small business recommends you stop after 600 or 800 grit. To protect the surface, he suggests you try a good quality automotive wax. You may want to try the wax on an extra piece or in a spot that isn't readily visible. ABS is impervious to most everything, but you never know.

Good luck,

Pat

[Maryw164]

Great idea! I'd much rather bring back the original finish than cover over it. Thanks for sharing. Please post how it all turns out.

[Chuck]

say, that looks great! but, won't it just re-yellow again? Thats why I'm thinking I might rather just paint it with the epoxy paint.

[Maryw164]

I looked a bit at your blog. Kudo's to all your hard work. I was just wondering why you chose to paint the endcap instead of the wet sanding like the bath. Isn't it made of ABS too? We need to do something with ours as it has yellowed, but since it has a imprinted pattern maybe it can't be sanded. Any thoughts?

Mary

[bmklawt]

MARYW164 I painted the endcaps because there is a texture to them that would be about impossible to sand out.

I recently found this thread http://www.airforums.com/forums/f39/...tic-50799.html and am trying it on the shower pan and sink at this moment. I have had this Retr0bright on for about an hour and all I can say is holy crap this stuff works good.
I wish I had known about this a month ago, I would have definitely tried this on the endcaps, looking at some of the before and after pictures from Retr0Bright - Using Retr0Bright it looks like it may leave the pattern that's printed on the ABS endcap in the front but even if it didn't who cares it would sure beat painting.

I have one piece of ABS with the print on that I have not touched yet I am going to try the Retr0bright on that just to see it will not harm the print.

[bmklawt]

I tried the Retr0bright on the kitchen window surround it is ABS plastic like the front endcap and has the same print on it. I did some testing before I painted my endcap and do know the print or design on the endcap can be taken off with MEK or Xylene.

The Retr0bright stuff lightens up the ABS plastic but does not touch the print. Wish I had heard about this sooner.

[Retr0bright]

Hi! I have just joined your forum as I noticed you were trying our creation out on your trailer parts. If you have any questions about how it works or how to use it, let's have them.

Cheers

Retr0bright aka Merlin

[tallytwo1994]

I have wondered if it will work for fiberglass too?

[dwightdi]

Fiberglass parts are thermal set (vs thermoplastic) and are coated with gelcoat, which is also thermal set. The ABS parts previously discussed are is partially dissolved by the solvent Retrobright puts in it. This allows the bleach they have included in their formula to interact more effectively. You could get some bleaching action on fiberglass by using wood bleach product or Oxi product. If the fiberglass is highly pigmented, most of the degradation occurs on the surface and the gelcoat is pretty thick. Therefore, you can sometimes sand off the surface to reveal an undegraded surface and repolish it to look pretty good. I have done that on fiberglas boats as much as 40 years old. If the fiberglass is not gelcoated or pigmented, such as the translucent rock guard on old trailers or astrodomes, this trick will not work. You can paint over the fiberglass to restore some appearance.

[Retr0bright]

@ dwightdi

Sorry, but you are wrong about this. Fibreglass resin is a polyester and is a thermoplastic resin. ABS is also a thermoplastic; you won't normally see thermosets unless you are using epichlorohydrin (epoxy), melamine formaldehyde or urea formaldehyde type resins. Thermosets are normally too brittle for boat and car applications.

Retr0bright has been proven NOT to dissolve plastic in any way, it's NOT a solvent; what we are treating with the Retr0bright is oxygen atoms that have become attached to the brominated flame retardant (TBBP-A actually) by hitting the bond with UV light. This destabilises the bond betweent eh oxygen and the flame retardant and allows a hydrogen atom from the unstable, catalysed peroxide mixture to attach itself to the bromine atom, effectively reducing the bromine back to it's original state and reversing the yellowing. The science behind this is fundamentally sound.

Anyway, what do I know? I've only been an industrial chemist for over 25 years, and I was the guy that developed this stuff......

Doesn't anyone read Wikis these days?

[dwightdi]

Thermoplastics resins are processed by melting and injection molded. Thermal set resins are processed by shaping them and then causing a chemical reaction to occur which causes them to become rigid. "Fiberglass" parts are made by soaking a fiberglass mat or cloth with a liquid polyester resin which has been catalyzed to reaction and form a solid. ABS stands for Acryonitrile, Butadiene, Styrene. It is a mixture of these three thermoplastic resins. The arrylonitrile gives it the strength, the butadiene is the rubber (which gives it its impact resistance) and the stryene makes it easily processed. The yellowing is caused by the double bond in the butadiene reacting to the UV in the sunlight and breaking the bond. That is why ABS degrades and loses its durability with long term sun exposure. Yellow color bodies are formed in the process. Most grades of ABS and "Fiberglass" do not contain any brominated fire retardents. Just call any plastics supplier to verify that. I have been a degreed plastics engineer for 45 years and have supplied millions of pounds of plastics to the industry. From the information given by Retrobright, their product appears to be principally an oxygen bleaching agent. This will bleach the color bodies formed by the degradation of the butadiene and restore the color, but will not restore the loss in ductile properties.

For the fiberglass, it will likely also bleach out any color bodies which were formed in the degradation of the cross linked polyester and styrene in the original part. Most fiberglass intended for long term outdoor exposure contain an additive to resist the UV exposure. I, at one time, manufactured this additive and sold it through Composites One, which is the largest fiberglass distributor network in the US.

Any high strength oxygen bleach would do the same. The two part "wood bleach" products usually produce the greatest oxygen bleaching effect.

[Retr0bright]

@ dwightdi

Thanks; it's not often that we come across guys that actually understand what we are on about here; it goes over most people's heads!

We have also identified that it has to be bromine bonds from the TBBP-A flame retardant (which was added to ABS in the 80s and 90s) at work causing the yellowing as well; Experiments carried out under no light conditions just get the parts wet and no reaction occurs. This is the basis of our theory that it is UV light vibrating the bromine-oxygen co-ordinate bonds, making them unstable and allowing us to remove the oxygen and replace it with a hydrogen from the catalysed peroxide solution. Since the hydrogen will form a covalent bond, it has a higher affinity for the bromine than the oxygen and the stoichiometry of the bonds is equal.

This is why we don't describe the process as 'bleaching' since it's not actually a bleaching process.

Overdoing the peroxide strength can induce attack on the polymer matrix via the butadiene bonds as you describe, which creates the 'bloom' as mentioned in our 'Problems and Pitfalls' section of the Wiki. We deliberately keep the H2O2 strength below 15% in order to try and prevent attack of the polymer.

There; that's the Science bit over.

By the way: adding Oxiclean to 35% H2O2 makes a bleach that leaves Wood Bleach behind! TAED is a phenomenal catalyst for this reaction, which is why they use it in the detergent additives.

[Chuck]

question on "UV light". I was looking through the selection of bulbs at the home center the other day, and I couldn't figure out exactly which kind would be appropriate for this. I was thinking "sun lamp" or "grow light", but I couldn't find anything that specifically stated those terms.
I know people with seasonal affective disorder who get depressed in winter from a lack of sunlight can get these "special" lights to sit near...I'm assuming thats the sort of thing that is needed here. But what is it called? what kind of fixture (flourescent?)?

[Retr0bright]

Chuck,

What you need is what people call a "black light", i.e. a standard dark purple UV bulb as sold in fancy dress shops and some hardware stores. It doesn't have to be anything fancy - the filament and energy saving types both work perfectly OK.

If you check the pictures of the C64 experiments Tonyyeb and I did in the gallery on the Wiki, you will see that we used energy saving bulbs.

If you search UV bulb on Ebay you will see what I mean, don't go spending a bundle on the bulb.

[critter]

WOW!
This is great and bout 35 feet over my head.I dont know bout all them tech terms but I do understand slobber it on and hose it off and itll make it white again.I wanna know bout the light too!

[Distantdrummer]

OK dwightdi what say you now?
Many of us non-sceintific commoners would like to know. Bleaching or otherwise it seems to have generated only reported excellent results.
In your opinion as an Airstream owner is there some negative to the "ductile" degradation?
What is the result of ductile degradation? Crumbling ? Brittleness? Fragility? or what?

thanks

[Maryw164]

Yes, this inquiring mind wants to know too. I don't want to do anything that will make the ABS more brittle than it already is from age, exposure, etc. Will using an oxy type cleaner lighten it and or make it brittle in any way?

Thanks, Mary

[Retr0bright]

In simple English, no it won't affect the ABS plastic at all; all Retr0bright does it treat the fire retardant, it leaves the plastic polymer alone, unless you overdo it by making the H2O2 strength too strong. About 10% H2O2 strength is just enough to treat the fire retardant without attacking the plastic polymer.

[critter]

Thanks Retro dude!
I can almost understand plain english......sometimes.....but i'll give her a shot and see how she works.